Current understanding of the physiologic mechanisms of intrapartum fetal asphyxial brain injury has suggested a strong association with multiorgan system injury. Thus the purpose here is to describe 14 cases of severe fetal brain injury with absent multiorgan system dysfunction (MSD). The study population was drawn from a national registry for brain injured infants. MSD was defined by clinical criteria demonstrated to reflect asphyxial injury to the pulmonary, renal, cardiac, hematologic, hepatic, and gastrointestinal systems. Involvement of one other organ in addition to the brain was defined as multiorgan system dysfunction. All infants were diagnosed with hypoxic-ischemic encephalopathy (HIE) in the neonatal period and went on to have permanent central nervous system (CNS) injury and MSD criteria were not met. Of the 292 term, singleton infants with HIE and permanent neurologic injury, 57 (20%) satisfied the entry criteria; of these, 14 (36%) had no MSD. The underlying basis for the fetal brain injury were: uterine rupture, 6 (43%), prolonged FHR deceleration, 5 (36%), fetal exsanguination, 1 (7%), cord prolapse, 1 (7%), and maternal cardiopulmonary arrest, 1 (7%). The mean duration of the prolonged FHR deceleration was 32.1 +/- 9.1 (range 19-51) minutes. All infants were later diagnosed with cerebral palsy. Intrapartum fetal asphyxial brain injury may not necessarily proceed through a physiologic mechanism in which the fetal circulation is centralized and endorgans damaged. These acute injuries, associated with a prolonged FHR deceleration, may be linked to severely decreased cardiac output and hypotension that cause vulnerable portions of the brain to be injured before other organs.